Archive for July 5, 2021

07/05/2021 – Ephemeris – Happy Aphelion Day

July 5, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, July 5th. Today the Sun will be up for 15 hours and 27 minutes, setting at 9:30, and it will rise tomorrow at 6:04. The Moon, halfway from last quarter to new, will rise at 3:24 tomorrow morning.

Today, the Moon and Sun are at their farthest from the Earth. For the Moon it’s called apogee, for the Sun it’s called aphelion. At 10:48 this morning the Moon will be at that point 251,842 miles (405,300 kilometers) away. The Sun will be farthest at 10:59 pm at a distance of 94 million, 452 thousand miles (152 million, 6 thousand kilometers) away. Because of the gravitational pull of the Moon and planets on the Earth, and the Pull of the planets, especially Jupiter on the Sun, the aphelion and perihelion or closest date in January don’t occur on the same date or same distance every year. The date wanders by a day or two each year. The entire distance variation for the Earth is plus or minus 1.5 million miles (2.4 million kilometers) over the year, but makes summer the longest season by a few days because the Earth moves slower when farther from the Sun, than when it is nearer.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4). They may be different for your location.


Earth's orbit

The Earth’s orbital ellipse, somewhat exaggerated, showing perihelion, aphelion and the seasons. Credit “Starts with a Bang” blog by Ethan Siegel.

Currently, summer is the longest season at 93.65 days, while winter is the shortest season at 88.99 days. (Source: Astronomical Tables of the Sun, Moon and Planets, Third Edition by Jean Meeus)